Seroimmune responses to strategic vaccination in chickens against Newcastle disease using commercially available vaccines
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Date
2014
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Publisher
Sokoine University of Agriculture
Abstract
Evaluation of the Newcastle Disease (ND) antibody level after different vaccination
strategies using 1-2 and La Sota vaccines was conducted on day old broiler chicks. Five
groups for each type of vaccine, containing sixteen (16) randomly assigned chicks each
were kept in none communicating pens. The chicks were accorded standard management
procedures including ad libitum feeds and water as well as deworming and vaccination
against fowl pox and infectious Bursa disease. At three weeks of age, chicks were wing
tagged and vaccination strategies employed. Vaccination strategies employed for each
vaccine type were 12.5%, 25% and 50%, the remained percentage was filled by in-contact
chicks. Vaccination at 100% and no vaccination (0%) served as controls. Blood samples
were collected before vaccination and then after every two weeks, five times post
vaccination. Sera were prepared and tested for antibodies against Newcastle Disease virus
using the standard Haemagglutination Inhibition (HI) procedure. At 12.5% vaccination
strategy for 1-2, only 12.5% of the vaccinated chickens had protective antibodies level (HI
titre results <log3 base 2) and none of the in contact chickens and the Geometric Mean
Titre (GMT) of 1.13 was recorded and was not significantly different (p>0.05) with that of
the negative control group. For La Sota vaccines at 12.5% strategy, 62.5% of the chickens
had protective antibodies level and the GMT of 3.31 was recorded and was not
significantly different (p>0.05) to the GMT of positive control group. At this strategy, La
Sota vaccine has proved to do better than 1-2 vaccine in activating immune response in
chickens. At 25% vaccination strategy, both 1-2 and La Sota vaccines showed that, 75% of
the chickens had protective antibodies level. The GMT was 2.5 and 3.06 for 1-2 and La
Sota respectively. These were significantly different (p<0.05) to GMT of the negative
controls.
Description
Dissertation
Keywords
Seroimmune responses, Strategic vaccination, Newcastle disease, Chickens